'Neda' four years later and other viral moments

Demonstrator holding a portrait of slain Iranian icon Neda Agha-Soltan during a protest following the Iranian election results, in Trieste, Italy, on June 25, 2009.
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Four years after a hotly contested presidential election, Iranians head back to the polls Friday. A lot has been said and written about the circumstances surrounding the 2009 vote as well as its aftermath. But one of the more lasting images came when a video captured the final moments of a young woman who bled to death after being shot during a Tehran demonstration.

(CBS)

Almost immediately, pictures of Neda Agha-Soltan went viral, and the 26-year-old music student turned into a symbol for the opposition challenging President Mahmoud Ahmadinejad's disputed re-election. Of course, Neda's was not the first image of personal tragedy to go global -- remember the picture of a 14-year-old runaway kneeling over the body of a shooting victim at Kent State in 1970? -- but the instantaneous transmission of Neda's picture around the world underscored how much smaller our global village had become. And in the subsequent four years, as the Internet spread even further, there was no shortage of extraordinary moments that became viral fodder for millions around the world.